Generator voltage regulator

Abstract

FIELD: electrical engineering.SUBSTANCE: invention relates to power supply systems. The regulator, having a positive input, a negative input and an output intended for connection to the generator, as well as a setpoint correction input, according to the invention has constant-error response S and is equipped with a valve and an integrating correction link, the output of which is connected through the valve to the setpoint correction input. The regulator setpoint correction input is designed as an output that allows connection to similar outputs of other regulators in the case of a parallel connection of several generators. A transistor switch or a semiconductor diode can be used as a valve.EFFECT: expansion of the functional capabilities of the regulator by unifying it for use in power supply systems with both one and several generators connected in parallel.6 cl, 5 dwg

Description

[0001] The invention relates to the field of electrical engineering, namely, to power supply systems and can be used primarily on transport vehicles, in particular, on large buses that have several generators connected in parallel.

[0002] There are numerous generator voltage regulator circuits (Akimov S.V., Chizhkov Yu.P., Electrical Equipment of Automobiles. Textbook for Universities. - Moscow: ZAO "KZhI "Za Rulem", 2004 - pp. 112-118), which are used in transport vehicles. The generator voltage regulator (hereinafter referred to as the regulator) has positive and negative inputs for connection to the generator's armature terminals, as well as an output for connection to the generator excitation winding. All electrical equipment in transport vehicles is critically dependent on the performance of regulators, so they are designed to be as simple and reliable as possible.

[0003] Regulators are either relay-based (with a variable frequency switching of the generator excitation winding) or pulse-width modulated (with a stabilized frequency switching of the generator excitation winding). In both cases, to reduce voltage regulation error, the regulators have virtually zero (insignificant) droop. A disadvantage of generator sets with such regulators is that when several generators are connected in parallel, the current is distributed extremely unevenly between them. This is explained by the technological spread of the regulator settings, due to which the generator with the highest setting bears the maximum load current; only after its voltage drops due to overload does the next generator begin operation.

[0004] A power supply system (US Patent 9,979,196 B2 - May 22, 2018) with parallel-connected generator sets is known. In this system, when an imbalance is detected, a portion of the electrical load is incrementally transferred from one generator set to another under the control of a system controller so that their operating loads tend to equalize. The disadvantages of this power supply system include:

[0005] - complexity associated with the presence of a special system controller and corresponding software;

[0006] - low degree of unification associated with the need to configure software for different implementations of the system.

[0007] A regulator included in the power supply system of a transport vehicle (Patent RU 2687246 C1 - published May 8, 2019) was selected as the prototype for the claimed technical solution. This system comprises a generator and a regulator with positive and negative inputs connected to the generator's anchor terminals, an output connected to the generator's excitation winding, and a reference signal generator with a correction input (setpoint correction input).

[0008] The disadvantage of the prototype is its limited functionality: the power of the power supply system cannot be increased by connecting several generators in parallel, since the regulators of these generators do not have the ability to proportionally distribute the load current between them.

[0009] The objective of the claimed invention is to expand the functional capabilities of the regulator.

[0010] The technical result that allows expanding the functionality of the regulator is that it should be unified for use in various power supply systems:

[0011] - in systems with one generator;

[0012] - in systems with several generators connected in parallel.

[0013] The solution to the problem of expanding the controller's functionality is achieved by the controller, which has a positive input, a negative input, and an output intended for connection to the generator, as well as a setpoint correction input. According to the invention, the controller has a droop S and is equipped with a valve and an integrating correction element, the output of which is connected via the valve to the setpoint correction input. The controller's setpoint correction input is designed as a terminal, enabling connection to similar terminals of other controllers in the event of a parallel connection of several generators.

[0014] A transistor switch or a semiconductor diode can be used as a valve - the choice is determined by the specific circuit implementation, and by connecting the setpoint correction inputs of several controllers, the following options are possible:

[0015] - transistor keys can form a selector of maximum, minimum, or arbitrary signal;

[0016] - forward-biased diodes form a maximum selector;

[0017] - Diodes connected in reverse direction form a minimum selector.

[0018] The regulator can be designed so that the regulated voltage—the voltage between the positive and negative inputs of the regulator—is applied to the input of the integrating correction element (series correction). Another possible implementation is one in which the input of the integrating correction element is connected to the output of the regulator (parallel correction). The choice of option depends on the specific circuit design of the regulator and does not affect the achievement of the claimed technical result.

[0019] The integrating correction element has a range of change of the output signal ADJ, reduced in magnitude to the generator voltage, not less than the static S

[0020]

[0021] where ADJmax, ADJmin are respectively the maximum and minimum possible values ​​of the ADJ signal, and the static S is the range of change of the steady-state voltage of the generator.

[0022] In a proportional (with static S) regulator, the generator voltage U tends to the value

[0023]

[0024] where REF(p) is the proportional controller setting, I is the current value of the generator current, Imax is the maximum permissible value of the generator current.

[0025] The static value S must be sufficient for proportional distribution of the generator current with an acceptable error in the case of their parallel connection.

[0026] The controller can be designed so that the required droop S is achieved by using additional feedback on the generator current, which is added to the feedback signal on the generator voltage U with a coefficient of SAmax. In this version of droop formation, the invariance of the regulated voltage with respect to changes in the generator rotation speed can be ensured, therefore this version is universal and can be used for parallel connection of generators of different types rotating at different speeds.

[0027] The regulator can also be designed so that the required static behavior is achieved by limiting the error gain in the control loop; this option is acceptable for parallel connection of generators of the same type with a drive from a common shaft.

[0028] A digital version of the controller circuit based on a microcontroller is possible. This circuit contains: a positive input, a negative input, an output, and an input for adjusting the controller setpoint; a reference voltage source; a transistor switch as a valve with a control input and a switched channel; an integrating correction element, which is a program for integrating the input signal with subsequent pulse-width modulation of the integration result at the output; a power switch; a proportional element, which is a program for multiplying the input signal by a proportionality coefficient with subsequent pulse-width modulation of the multiplication result at the output; a summing divider on three resistors; a divider on two resistors, and a capacitor. The digital version can also contain a LIN transceiver that connects the microcontroller to the communication bus of the transport vehicle. The common wire of the circuit can be either the negative or positive input of the controller.The output of the integrating correction element is connected to the control input of the transistor switch, whose commutated channel is connected to the setpoint correction input and the common wire. The power supply terminals of the power switch are connected to the positive and negative inputs of the regulator, and the output is the regulator output. The control input of the power switch is connected to the output of the proportional element, whose input is fed with the difference between the reference voltage and the output voltage of a summing divider with three resistors. One input of the summing divider with three resistors is connected to the setpoint correction input, and the other is fed with the feedback voltage. The feedback voltage can be a function of the armature voltage, armature current, and generator rotation speed. The input of the integrating correction element is fed with the difference between the reference voltage and the output voltage of the divider with two resistors connected to the positive and negative inputs of the regulator.The output of the summing divider on three resistors is connected through a capacitor to the common wire.

[0029] An analog version of the controller circuit design is possible. This circuit contains: a positive input, a negative input, an output, and a setpoint correction input for the controller; a reference voltage source; a diode as a valve that can be connected in the forward or reverse direction; an integrating correction element with an analog output signal; a power switch; a proportional element, which includes a comparator and a sawtooth voltage generator; a summing divider on three resistors; a divider on two resistors; an inverting follower and a resistor. The common wire of the circuit can be either the negative or positive input of the controller. The setpoint correction input is connected through a diode to the output of the integrating correction element. The power supply terminals of the power switch are connected to the positive and negative inputs of the controller, and the output is the output of the controller.The power switch control input is connected to the output of the proportional link, whose input is fed with the output voltage of a summing divider with three resistors. One input of the summing divider with three resistors is connected via an inverting follower to the setpoint correction input, and the other is fed with the feedback voltage. The feedback voltage can be a function of the armature voltage, armature current, and generator speed. The input of the integrating correction link is fed with the difference between the reference voltage and the output voltage of the divider with two resistors connected to the positive and negative inputs of the controller. The comparator output is the output of the proportional link. One comparator input is the input of the proportional link, and the other is connected to the output of the sawtooth generator. To prevent the inverting follower from operating in open-loop mode, the latter is connected to the ground via a resistor.

[0030] The digital and analog versions of the regulator circuits described above are not exhaustive - other options for constructing circuits with the same set of essential features are also possible.

[0031] The vehicle's power supply network typically includes loads, a battery, and the armature terminals of one or more parallel-connected generators. When using the proposed regulators, each generator is equipped with one, with the positive and negative inputs of each regulator connected in parallel to the armature terminals, and the output connected to the excitation winding of the corresponding generator. The setpoint adjustment inputs of all regulators must be combined.

[0032] Research conducted using patent and scientific and technical sources of information indicates that the claimed regulator contains a set of essential features not identified in the prior art, and the impact of these distinctive features on the technical result is not obvious. Therefore, the proposed regulator meets the criteria of "novelty" and "inventive step." The essential features of the proposed solution influence the achievement of the technical result as follows:

[0033] - It's common knowledge that the regulator has a positive input, a negative input, and an output, designed for connection to a generator. These features allow the regulator to be used in traditional single-generator systems, but do not provide proportional distribution of the load current between multiple generators connected in parallel.

[0034] - proportional distribution of the load current in systems with multiple generators is ensured by the fact that the regulator has static S. This technique is known from the theory of automatic regulation, but its implementation increases the error in voltage regulation, which is unacceptable for power supply systems of transport vehicles;

[0035] —the set of features that ensures the stated technical result is achieved by the controller being equipped with a valve and an integrating correction element, the output of which is connected via the valve to the setpoint correction input. In systems with a single generator, the controller, which exhibits droop, together with the integrating correction element, operates as a PI controller. In systems with multiple generators, each equipped with a controller, the setpoint correction inputs of these controllers should be combined. The valves will be interconnected via the setpoint correction inputs, forming a signal selector that will select one of the integrating correction elements as the master element for all controllers. This resolves the contradiction between the need to ensure significant droop for each individual controller and the need to ensure virtually zero (insignificant) droop for the system as a whole.

[0036] The claimed technical solution is explained by drawings.

[0037] Fig. 1 contains a circuit diagram of a regulator with a valve in the form of a transistor switch.

[0038] Fig. 2 contains a regulator circuit with a valve in the form of a diode connected in the forward direction.

[0039] Fig. 3 contains a regulator circuit with a valve in the form of a diode connected in the reverse direction.

[0040] Fig. 4 contains a diagram of a power supply system using the proposed regulator.

[0041] Fig. 5 illustrates the current distribution of the generators.

[0042] The regulator circuit variant (Fig. 1) is digital and built on a microcontroller. The circuit contains:

[0043] - controller 1 with positive input 2, negative input 3, output 4 and setpoint correction input 5;

[0044] - source (not shown in the diagram) of reference voltage ref;

[0045] - transistor key 6 as a valve, which has a control input and a switched channel;

[0046] - integrating correction link 7, which is a program for integrating the input signal and pulse-width modulation (PWM) of the output signal;

[0047] - power key 8;

[0048] - proportional link 9, which is a program for multiplying the input signal by the proportionality coefficient (K) and pulse-width modulation (PWM) of the output signal;

[0049] - summing divider on resistors 10, 11, 12;

[0050] - divider on resistors 13,14;

[0051] - capacitor 15;

[0052] - LIN transceiver (not shown in the diagram) for connecting the microcontroller to the communication bus of the transport vehicle.

[0053] Positive input 2 and negative input 3 of controller 1 are used to connect to the generator armature, while output 4 is used to connect to the generator excitation winding; negative input 3 is the common wire of the circuit. The output of integrating correction element 7 is connected to the control input of transistor switch 6, the switching channel of which is connected to input 5 of the setpoint correction and the common wire. The power supply terminals of the power switch 8 are connected to the positive input 2 and the negative input 3 of the controller 1, and the output is output 4 of the controller 1. The control input of the power switch 8 is connected to the output of the proportional link 9, to the input of which the difference between the reference voltage ref and the output voltage of the summing divider on the resistors 10, 11, 12 is fed. Voltage adj from input 5 of the setpoint correction is fed to one input of the summing divider on the resistors 10, 11, 12, and feedback voltage fb is fed to the other.In general, the feedback voltage can be a function of the armature voltage, armature current, and generator speed. In this example, the feedback voltage fb is equal to the generator's armature voltage, that is, it is supplied from positive input 2 of controller 1. The difference between the reference voltage ref and the output voltage of the divider on resistors 13, 14, connected to positive input 2 and negative input 3 of controller 1, is supplied to the input of the integrating correction element 7. The output of the summing divider on resistors 10, 11, 12 is connected to the common wire via capacitor 15.

[0054] The regulator circuit variants (Fig. 2 and Fig. 3) are analog. The circuits contain:

[0055] - controller 1 with positive input 2, negative input 3, output 4 and setpoint correction input 5;

[0056] - source (not shown in the diagrams) of reference voltage ref;

[0057] - diode 6 as a valve (in the circuit in Fig. 2 the diode is connected in the forward direction, and in the circuit in Fig. 3 - in the reverse direction);

[0058] - integrating correction link 7 with analog output signal;

[0059] - power key 8;

[0060] - proportional link 9, which includes comparator 16 and sawtooth voltage generator 17;

[0061] - summing divider on resistors 10, 11, 12;

[0062] - divider on resistors 13,14;

[0063] - inverting repeater 18;

[0064] - resistor 19.

[0065] Positive input 2 and negative input 3 of regulator 1 are used to connect to the generator armature, and output 4 is used to connect to the generator excitation winding. In the circuit diagram in Fig. 2, the common wire is negative input 3, and in the circuit diagram in Fig. 3 - positive input 2 of controller 1. Input 5 of the setpoint correction is connected via diode 6 to the output of the integrating correction element 7. The power supply terminals of power switch 8 are connected to positive 2 and negative 3 inputs of controller 1, and the output is output 4 of controller 1. The control input of power switch 8 is connected to the output of proportional element 9, to the input of which the output voltage of the summing divider on resistors 10, 11, 12 is fed. Voltage adj from input 5 of the setpoint correction is fed to one input of the summing divider on resistors 10, 11, 12 through inverting follower 18, and feedback voltage fb is fed to the other. In general, the feedback voltage can be a function of the armature voltage, armature current and generator rotation speed.In the example under consideration, the feedback voltage fb is equal to the generator's armature voltage, i.e., it is supplied from the positive input 2 of the regulator (for the circuit variant in Fig. 2) or from the negative input 3 of the regulator (for the circuit variant in Fig. 3). The difference between the reference voltage ref and the output voltage of the divider on resistors 13, 14, connected to the positive 2 and negative 3 inputs of regulator 1, is supplied to the input of the integrating correction element 7. The output of comparator 16 is the output of proportional element 9. One input of comparator 16 is the input of proportional element 9, and the other is connected to the output of sawtooth voltage generator 17. To prevent operation of inverting follower 18 in the open-ended input mode, the latter is connected to the common wire via resistor 19.

[0066] The diagram of the power supply system using the proposed regulator (Fig. 4) shows:

[0067] - a set of controllers 1, each of which has a positive input 2, a negative input 3, an output 4 and a setpoint correction input 5;

[0068] - power supply network of the transport vehicle with positive wire 20 and negative wire 21;

[0069] - load 22;

[0070] - battery 23;

[0071] - anchors 24 and excitation windings 25 of a plurality of generators;

[0072] - communication line 26;

[0073] - communication bus 27 of transport vehicle (optional).

[0074] Loads 22, a battery 23, and the terminals of armatures 24 of several generators are connected in parallel to the positive wire 20 and the negative wire 21 of the power supply system. Each generator is equipped with a regulator 1, the positive input 2 and negative input 3 of which are connected in parallel to the terminals of armature 24, and the output 4 is connected to the excitation winding 25 of the corresponding generator. The setpoint correction inputs 5 of all regulators 1 are connected via a communication line 26. Regulators 1 can be connected to the communication bus 27 of the transport vehicle, for example, via the LIN communication protocol.

[0075] Fig. 5 shows the volt-ampere characteristics (VAC) for the case of a parallel connection of two generators:

[0076] - I-V characteristic 31 of one of the generators and the total I-V characteristic 32 of two generators at a load close to zero;

[0077] - I-V characteristic 33 of one of the generators and the total I-V characteristic 34 of two generators at a load close to maximum.

[0078] The operating principle of the regulator is explained using the example of the circuit in Fig. 1.

[0079] In the single generator mode, input 5 of the setpoint correction is not used for external connections and the value of the adj signal is determined by the state of the switched channel of the transistor switch 6. If the output voltage of the divider on resistors 13,14 is greater than the reference voltage ref, then the signal at the output of the integrating correction element 7 is equal to logical zero and the switched channel of the transistor switch 6 is open, otherwise it is closed.

[0080] Let's consider the state when the switched channel of transistor switch 6 is open, while:

[0081] - the voltage at the output of the summing divider on resistors 10, 11, 12 is proportional to the fb feedback signal;

[0082] - proportional link 9 in combination with power key 8 operates as a static (proportional) regulator;

[0083] - the regulated voltage U of the generator decreases with the increase of the generator current in accordance with expression (2).

[0084] Let's consider the state when the switched channel of transistor switch 6 is periodically closed, while:

[0085] - integrating correction link 7 reduces the value of the adj signal and, accordingly, the voltage at the output of the summing divider on resistors 10, 11, 12 (the adj signal is averaged by capacitor 15);

[0086] - proportional link 9 in combination with power switch 8 increases the regulated voltage;

[0087] - the output voltage of the divider on resistors 13, 14 is automatically maintained equal to the reference voltage ref due to the action of negative feedback, that is, the circuit operates as a proportional-integral controller (PI controller);

[0088] - PI controller setpoint

[0089]

[0090] where R13 is the resistance of resistor 13, R14 is the resistance of resistor 14.

[0091] In the mode of operation with multiple generators, each equipped with the claimed controller 1, the setpoint correction inputs 5 of these controllers are connected by a communication line 26 in accordance with Fig. 4. The setpoints of the multiple controllers have a technological spread. The controller with the maximum setpoint maintains the regulated voltage U of the generator at the level of the maximum setpoint REF in accordance with formula (3). In this case, for controllers with a lower setpoint:

[0092] - the signal at the output of the integrating correction links 7 is equal to logical zero;

[0093] - the switched channels of transistor keys 6 are open;

[0094] - the value of the adj signal is the same for all controllers and is set by the controller with the maximum setting.

[0095] Thus, the integrating correcting link 7, which is part of the controller with the maximum setting, is the leading one.

[0096] Another method of selecting the master link is also possible - by sending a command via the communication bus 27. In this case, the microcontroller, on the basis of which the circuit in Fig. 1 is implemented, will forcibly set the outputs of all integrating correcting links (except for one - the master) to the zero state.

[0097] The power supply system shown in Fig. 4 is astatic, but each of its controllers has a droop S, which ensures proportional distribution of the generator current. This is illustrated by the graphs shown in Fig. 5 for the case of a parallel connection of two generators:

[0098] - the output signal of the leading integrating correction link changes the signal at input 5 of the setpoint correction;

[0099] - since the 5 setpoint correction inputs are connected by communication line 26, the REF(p) setpoints of the proportional controllers change

[0100]

[0101] where ADJ is the value of the output signal of the leading integrating correcting link, reduced to the generator voltage;

[0102] - VAC 31, 33 represent the dependence of voltage U on the load current I of one of the generators and are constructed on the basis of expressions (2) and (4);

[0103] - if the static S of both regulators is approximately the same, then the slope of the I-V characteristic 31, 33 of one generator is approximately twice the slope of the I-V characteristic 32, 34 of two parallel-connected generators;

[0104] - since the generators are connected in parallel, their voltages U are the same and equal to the REF setting, and the currents I 31 , I 32 , I 33 , I 34 are determined by the intersection of the corresponding current-voltage characteristics 31, 32, 33, 34 with the line U=REF;

[0105] - regardless of the load current, the following relations are valid

[0106]

[0107] That is, the current of two parallel-connected generators is approximately twice the current of one generator.

[0108] The regulators shown in the diagrams of Fig. 2 and Fig. 3 operate on the same principle as the regulator in the diagram of Fig. 1. The difference lies in the valve connection circuit and the algorithm for selecting the leading integrating corrective element 7.

Claims

1. A generator voltage regulator having a positive input, a negative input, an output, and a setpoint correction input, characterized in that it has static S and is equipped with a valve and an integrating correction element, the output of which is connected through the valve to the setpoint correction input.

2. The regulator according to paragraph 1, characterized in that the setpoint correction input is designed as an output that allows connection to similar outputs of other regulators.

3. A regulator according to paragraph 2, characterized in that the integrating correcting element is made with pulse-width modulation of the output signal, and a transistor switch with a control input connected to the output of the integrating correcting element and a switched channel connected to the setpoint correction input is used as a valve.

4. The regulator according to paragraph 2, characterized in that the integrating correcting element has an analog output, and a semiconductor diode connected in the forward or reverse direction is used as a valve.

5. The regulator according to paragraph 1, characterized in that the integrating correcting link has a range of change of the output signal, reduced in magnitude to the generator voltage, not less than the static S.

6. The regulator according to paragraph 5, characterized in that the value of static S is sufficient for proportional distribution of the generator current with an acceptable error in the case of their parallel connection.

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